Corn is an important and valuable field crop. Thus, a continuing goal of plant breeding is to develop stable, high yielding corn hybrids that are agronomically sound. The reasons for this goal are obvious: To maximize the amount of grain produced on the land and to supply food for both animals and humans.
The overall goal of a corn plant breeder is to combine, in a single variety/hybrid, various desirable traits of the parental lines. For field crops, these traits may include resistance to diseases and insects, tolerance to heat and drought, reducing time to crop maturity, greater yield, and better agronomic qualities. The mechanical harvesting of many crops has placed increased importance on the uniformity of plant characteristics such as germination, stand establishment, growth rate to maturity, and fruit size.
In order to have the plants stand tall and withstand the various mechanical forces applied by wind, rain, harvesting equipment, etc., it is important that the plant stalk have good mechanical properties and that the roots are firmly anchored into the soil. Otherwise, the stalks may bend, break or be pulled out, leading to the loss of a harvestable ear.
It has become common place for corn plant breeders to use a set of fairly standard definitions for characterization of the mechanical properties of roots and stalks. For example, brittle snap is a measure of the stalk breakage below the ear during ear development and is an indication of whether a hybrid will snap or break near the time of flowering, under severe winds. Data is often presented as a percentage of plants that do not snap after a wind event.
Stalk lodging, is a trait measured near harvest time, and is scored as the percentage of plants that do not exhibit stalk breakage at the base of the plant, when measured either by observation of natural lodging in the field, or by physically pushing on stalks, and then determining the percentage of plants that break or do not break at the base of the plant.
Root lodging is a trait scored as the percentage of plants in a plot or field that do not exhibit excess leaning of the plant from the normal vertical axis. Typically, plants that lean from the vertical axis at an approximately 30 degree angle or greater would be counted as lodged. Root lodging often is reported as a rating of one to nine where a higher score indicates less root lodging potential (one is very poor, five is intermediate, and nine is very good, respectively for resistance to root lodging). There are two types of root lodging, early root lodging and late root lodging. Early root lodging occurs right before flowering. Late root lodging occurs within approximately two weeks of anticipated harvest or after pollination. Late root lodging is more problematic because of the inability of the plant to recover before harvest, which results in consequent yield losses.
Both early and late root lodging occur as a result of the interaction between the root system, the soil and the wind force pushing the plants during a storm. In moisture saturated soils, frictional forces between the root system and the soil particles are significantly reduced allowing the root to rotate when a lateral force is applied to the stalks. This rotation is in the direction of the force vector after the consequent lodging.
As those skilled in agricultural arts know, nearly every part of the corn plant has a use. Corn is used as human food, livestock feed, and as a raw material in many industries. The food uses of corn, in addition to human consumption of corn kernels, include products of both dry- and wet-milling industries. The principal products of corn dry milling are grits, meal and flour, while the corn wet-milling industry provides starch, syrups, and dextrose for food use. Corn oil is recovered from corn germ, which is a by-product of both dry- and wet-milling industries.
Corn is also used extensively as livestock feed primarily for beef cattle, dairy cattle, hogs, and poultry.
Industrial uses of corn are mainly from corn starch, from the wet-milling industry, and corn flour from the dry-milling industry. The industrial applications of corn starch and flour are based on its functional properties, such as, viscosity, film formation, adhesive properties, and the ability to suspend particles. Corn starch and flour have applications in both the paper and textile industries. Other industrial uses include applications in adhesives, building materials, foundry binders, laundry starches, explosives, oil-well muds, other mining applications, and for ethanol production.
Plant parts other than the grain of corn are also used in industry. Stalks and husks are made into paper and wallboard and cobs are used for fuel and to make charcoal.
Growers thus are interested in producing corn plants that have the very best grain or plant quality properties, produce the highest yield and therefore have the greatest potential for income.
An embodiment of the present invention provides a method and means of objectively measuring the susceptibility of corn plants to root lodging.
A further embodiment of the present invention provides a device which objectively measures corn plants' susceptibility to root lodging that is relatively inexpensive, easy to make and easy to use.
An embodiment of the present invention provides a method and device that can be used to test more effectively a hybrid's susceptibility to root lodging earlier in the product development cycle of a new hybrid than existing standard methods. Moving the testing for this trait much earlier in the development cycle allows for selection and advancement of the more desirable lines more easily, and at a point in the process when seeds of a new hybrid are relatively limited in numbers, which poses constraints with traditional methods that typically require more plants per hybrid for evaluation of root lodging. Also, traditional methods of scoring for such lodging depend on growing the plants in many locations in an attempt to have some locations present where naturally occurring environmental conditions occur, especially damaging winds that occur at key developmental stages. The present invention allows testing of the plants as needed, and is not dependent on the chance that a damaging wind might or might not occur, and so provides for a more reliable and resource efficient approach to testing for such traits. These embodiments as well as numerous benefits of the present invention will become apparent from the detailed description of the invention which follows hereinafter.